NTSB Identification: FTW01LA005.
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Accident occurred Wednesday, October 04, 2000 in IMPERIAL, TX
Probable Cause Approval Date: 07/10/2001
Aircraft: HOLT THORPE T-18C, registration: N85LH
Injuries: 2 Fatal.

NTSB investigators may have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

According to witnesses, the amateur-built experimental airplane was in cruise flight between 1,500 and 2,500 feet agl, when they heard a loud noise and observed pieces of the airplane separate from the airframe. Subsequently, the airplane entered a descent and impacted the ground. A fire erupted and consumed the airplane. Examination of the airplane revealed that a propeller blade separated 14.5 inches from the butt end. The blade failed due to fatigue initiating from an intergranular corrosion crack. According to the manufacturer's recommended interval between overhauls, the blade was four years overdue for an overhaul. An overhaul could have detected the corrosion crack that led to the failure. Additionally, each blade had been shortened approximately 6 inches since it was originally manufactured, and the propeller was not approved by the manufacturer for installation on the type of engine in the airplane.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

the failure of the propeller blade due to fatigue, which originated from a corrosion crack. A contributory factor was the pilot/owner's failure to ensure that the propeller was overhauled at the manufacturer's recommended interval.

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